I installed a Verizon Range Extender about 2 1/2 years ago and when it works it is flawless, but it is quirky.

The concept behind the Range Extender is elegant and simple. If you find yourself in a cellphone dead zone but have broadband Internet access, just plug in a Range Extender, attach a Cat 5 cable to your network, put its GPS antenna in a south-facing window, and voila! Your cellphone traffic is routed through the broadband connection to the Verizon mother ship. The GPS sensor on the Range Extender provides your physical location to your cellphones to meet FCC requirements for 911 calls.

The Range Extender has four LEDs on the front: Power, GPS, Internet and SYS. When these LEDs all show blue, the Range Extender is up and running, awaiting your outbound calls and routing incoming calls to you.

The Range Extender list price of $250 is a bit steep given the device offloads Verizon's heavily loaded cell towers and using it adds billable cellphone minutes, both of which work in Verizon's favor. If you have several Verizon phones, you can probably negotiate a discount of about half.

So where does the Range Extender concept break down? The obvious time is when your broadband link is out of service. Not much to do about that, except to wait for your ISP or your electric company to get back up and running.

But, if you are suddenly without cellphone service when Verizon's Internet-based cellphone system goes down, be prepared for long hours on the phone with Verizon techs to troubleshoot. First, they may try to lay the blame on your ISP. Next, they might tell you that your Range Extender is faulty and needs to be replaced. Once, after three days out of service and numerous calls to Verizon, our Range Extender magically started working again, and Verizon gave us full credit for a month of service on all our cellphones.

Another shortcoming has to do with cloudy and foggy weather, a common occurrence in my New England area, especially in the winter. A heavily overcast sky causes the device to lose the GPS satellite signal, the GPS LED goes red, and all cellphones stop working. Here in New England, that means the phone link could be out for a long time. The recovery procedure is to unplug and replug the Range Extender repeatedly until it finally gets a GPS signal, definitely hit or miss.

Unlike a cellphone, however, the Range Extender tends to stay in one place, so it could have been designed to get a GPS signal once, just after being plugged in. After that, it could keep the GPS coordinates in memory and never have to search for the GPS satellite until it is powered off/on again. A further refinement would be to put a "Sense GPS" button on the front, to be used only when the Range Extender gets moved to a new location. Of course, when a Range Extender is powered up for the very first time out of the box, it must find a GPS satellite to get its own coordinates.

The Range Extender is also a closed system. It does not respond to a network ping, so you have no idea what its IP address is. Worse yet, its IP address may duplicate that of a computer or network printer, causing network chaos. And, of course, it does not provide any Web browser access to its settings and status, so you have no idea what is going on except for the idiot-light LEDs on the front and a blinking Ethernet pulse on the back. This makes troubleshooting a virtual impossibility, and complicates matters when a Range Extender is several rooms away or on another floor.

Despite its shortcomings, the Verizon Range Extender solves the cellphone dead zone problem, and it is better than nothing at all. Most of the time. It is suitable for use in home offices and other small offices. But anyone with a network of, say, 10 or more computers to administer needs a far more robust Internet cellphone product.